Recently, secondary batteries are widely used for not only small-scale apparatuses such as portable electronic apparatuses but also medium and large-scale apparatuses such as automobiles or power storage apparatuses. Particularly, as carbon energy is gradually exhausted and an interest on an environment increases, hybrid automobiles and electric automobiles are drawing public attention all over the world including the United States, Europe, Japan, and South Korea.
Most essential part in the hybrid automobiles or electric automobiles is a secondary battery pack giving driving force to a motor of automobiles. Since the hybrid automobiles or electric automobiles may obtain driving force of the automobiles through charging/discharging of the secondary battery pack, the hybrid automobiles or electric automobiles have lots of advantages in various aspects such as excellent gas mileage, and non-exhaustion or reduction of polluted materials compared to automobiles which use an engine only, so users of the hybrid automobiles or electric automobiles increase gradually.
In a secondary battery pack applied to an electric automobile, lots of secondary batteries are electrically connected in order to increase a capacity and power thereof. In this case, for a unit secondary battery, a pouch type-secondary battery which may be easily stacked and allow space-intensive arrangement is widely used.
However, since a pouch type-secondary battery is packed with a battery case of a laminated sheet including aluminum and a polymer resin in general, mechanical strength thereof is not large. Therefore, when configuring a secondary battery pack including a plurality of pouch type-secondary batteries, a cartridge is generally used in order to protect the secondary batteries from an external impact, etc., prevent moving thereof, and facilitate stacking. The cartridge may be replaced with various other terms such as a frame for stacking. Also, a plurality of cartridges are used in a stacked form to configure a secondary battery pack, and the secondary batteries may be arranged in an inner empty space generated when the cartridges are stacked.
Meanwhile, in the case of assembling a plurality of secondary batteries by using a plurality of cartridges, a plate-shaped cooling fin, that is, a cooling plate may be interposed between the secondary batteries. A secondary battery may be used under a high-temperature environment such as summer and also the secondary battery itself may emit heat. In this case, in the case where a plurality of secondary batteries are mutually stacked, the temperature of the secondary battery may be raised even more. When the temperature is higher than an appropriate temperature, the performance of the secondary battery may deteriorate, and in a serious case, there is a danger of explosion or ignition. Therefore, a configuration of interposing a cooling plate between secondary batteries when configuring a secondary battery pack, and preventing a temperature rise of the secondary battery through the cooling plate may be used.
In the secondary battery pack in which the cooling plate is interposed between the secondary batteries, the secondary battery may be cooled down in various forms and methods. As a representative method among cooling methods, air cooling of lowering the temperature of a secondary battery through heat exchange between a cooling plate and air by allowing external air to flow around the cooling plate is widely used. The secondary battery which cools down the secondary battery through air cooling allows air to flow in and out between the inside and outside of the secondary battery pack by securing a cooling channel around the cooling plate and connecting the cooling channel to a duct.
Meanwhile, in an air-cooled structure of a conventional secondary battery pack, a plurality of cooling channels are provided along a cartridge stacking direction and a duct is arranged across the cooling channels in general. In this case, separation of air occurs at the end of the cooling channel where an air channel drastically changes and so turbulence occurs. This turbulence hinders an air flow inside the secondary battery pack. When an air flow inside the secondary battery pack becomes bad, a cooling performance of the secondary battery may deteriorate, and an energy efficiency of an apparatus forcibly flowing air, for example, a cooler such as a ventilation fan is reduced.